Using the regional climate model WRF, and the NCEP-NCAR Reanalysis Project data asboundary and initial conditions, regional precipitation was estimated by means of thedynamical downscaling technique for two selected periods, January 2000 and September2007. These months show very particular climatic characteristics of the precipitationregimen in Central America, like dry (wet) conditions in the Pacific (Caribbean) coast of theCentral American isthmus, in January, and wet (dry) conditions, respectively in each coast,during September. Four-nested-domains, each grids of resolution of 90 km (d01), 30 km(d02), 10 km (d03), and 3.3 km (d04), were configured over this region. The runs werereinitialized each 5 days with 6 hours of spin-up time for adjustment of the model. A total of8 experiments (4 per month) were tested in order to study: a) two important CumulusParameterization Schemes (CPS), Kain-Fritsch (KF) and Grell-Devenyi (GD); and b) thephysical interaction between nested domains (one- and two-way nesting), during eachsimulated month.January 2000 results showed that the modeled precipitation is in agreement withobservations, and also captured the mean climate features of rainfall concerning magnitude,and spatial distribution, like the particular precipitation contrast between the Pacific and theCaribbean coast.Outputs from September 2007 revealed significant differences when a visual comparison ismade to the spatial distribution of each coarse domain (d01, d02, and d03) with theirrespective domain in each experiment. However, the inner grids (d04) in all theexperiments, showed a similar spatial distribution and magnitude estimation, mainly inthose runs using one-way nesting configuration. Furthermore, the results for this mothdiffer substantially with observations, and the latter could be related with associateddeficiencies in the boundary condition that do not reproduce well the transition periodsfrom warm to cold El Niño episodes.Moreover, in all the experiments, the KF scheme calculated more precipitation than the GDscheme and it is associated to the ability of the GD scheme to reproduce spotty but intenserainfall, and apparently, this scheme is reluctant to activate, frequently yielding little or norain. However, when rainfall does develop, it is very intense.Also, the time series do not replicate specific precipitation events, thus, the 5-daysintegration period used in this study, is not enough to reproduce short-period precipitationevents.Finally, physical interaction issues between the nested domains are reflected indiscontinuities in the precipitation field, which have been associated to mass fieldadjustment in the CPS. / Nederbörden i Central Amerika har uppskattats med dynamisk nedskalning för två utvaldaperioder, januari 2000 och september 2007. Global återanalysdata från NCEP-NCARsåteranalysprojekt har använts som randdata och initialdata till den regionalaklimatmodellen WRF. De studerade månaderna uppvisar stora variationer inederbördsmönster, t ex lite (mycket) nederbörd under januari och mycket (lite) nederbördunder september för kustområdena längs Stilla havet (Karibiska havet). Fyra nästladedomäner över Central Amerika har använts med en upplösning på 90 km (d01), 30 km (d02),10 km (d03) och 3,3 km (d04). Simuleringarna initialiserades var 5:e dag och de första 6timmarna efter varje initialisering används för modellens anpassning till initialtillståndet.Totalt 8 experiment genomfördes (4 för varje månad) för att studera: (a) två olika sätt attparameterisera konvektion i Cumulusmoln (CPS), Kain-Fritsch (KF) och Grell-Devenyi (GD)och (b) den fysikaliska interaktionen mellan de nästlade domänerna (en- respektive tvåvägsnästlade scheman).För januari 2000 var det god överensstämmelse mellan modellerad och observeradnederbörd. Modellen beskriver väl såväl mängden nederbörd som den rumsligafördelningen, t ex den stora kontrasten mellan kustområdena längs Stilla havet och Karibiskahavet.För september 2007 uppvisar den modellerade nederbörden stora skillnader i de olikaexperimenten för de yttre domänerna (d01, d02, d03). För den inre domänen (d04) ärresultaten från de olika experimenten betydligt mer lika, särskilt för experimenten medenvägs nästlade scheman. Vidare skiljer sig den modellerade nederbörden väsentligt frånobserverad nederbörd under september 2007. Detta kan förklaras med felaktiga randdatapå grund av problemet i återanalys data att reproducera perioder med övergång från varmtill kall El Niño. I alla experiment gav KF mer nederbörd än GD, det kan förklaras med att GDbättre reproducerar kortvarig, intensiv nederbörd. Det finns en viss tröghet innannederbörden i GD aktiveras, vilket innebär större frekvens av lite eller ingen nederbörd. Närnederbörden väl utvecklas blir den dock intensiv. WRF-modellen klarar inte av att återgespecifika nederbördshändelser för de genomförda experimenten, vilket betyder att 5-dagarär för lång simuleringstid för att kunna reproducera specifika händelser. Slutligen,interaktion mellan de nästlade domänerna skapar diskontinuiteter i nederbördsmöns.

The main objective of the dissertation is to develop a dynamic, inter-regional, and multi-sector general equilibrium model of the Belgian economy capable of analysing issues related to the environment, energy, fiscal policies and accounting for distributive effects between household groups. The dissertation focuses on BelMod, a computable general equilibrium model (CGE).<p>BelMod is intended to act as an analytical and quantitative support for decision-making in the energy/environment field and fiscal policies. The tool would be in evaluating ex-ante the cost and benefit of different policies to be implemented. The winners and the losers may easily be identified. BelMod also aims at filling the gaps left by the other models currently used in Belgium, in particular by explicit bottom-up modelling of the three Belgian regions (Brussels, Flanders, Wallonia) in the full integrated framework, by further disaggregating the production and consumption blocks, by distinguishing different types of households to study the distributional effects of environmental and fiscal policies.<p>The effect of let’s say, carbon tax, may affect branches of activities, markets and institutions differently over time and space. Under the “Burden Sharing Agreement”, Belgium committed to reduce its greenhouse gas emissions by 7.5 % by 2008-2012 from the 1990 level. Therefore the efficient way of dealing with this issue requires an analytical tool which can take into account the interactions between institutional agents (regional governments, community’s governments, central government, households, firms and rest of the world), their behaviour and the time horizon. The most adequate tool to do so is the general equilibrium model.<p>A CGE model such as BelMod requires a consistent, detailed and well structured database in the form of a social accounting matrix (SAM). A SAM is a square matrix which takes into account the production, consumption, revenues, expenditures and transactions of institutions at a given period of time. The reference year for our SAM is 2003. The SAM we built contains sixty two (62) branches of activity, sixty nine (69) commodities, three (3) regional governments, the French Community, the Central Government, the capital accounts and the Rest of the World.<p>Finally, to illustrate the capabilities of the model we provide two scenario analyses. In the first policy scenario, we simulate the introduction of a carbon tax at 20 euro per ton of CO2 emissions in 2013-2020 and 30 euro per ton of CO2 emissions in 2021-2050. In the second policy scenario, we simulate a linear and gradual increase of the crude oil price to 150 US dollars per barrel in 2050. The increase starts in 2008 and the target (150 US dollars) is reached in 2050.<p> / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished